In reply to Postmanpat:
> Genuine question: from the outside it looked very sudden but maybe it had been coming for years?
To be honest, if you think it was sudden rather than inevitable then you sound completely out of touch. Possibly as out of touch as I may be with English politics! The polls were right. 56 SNP seats is lower than the more speculative poll based predictions.
> Was it because most Scots now genuinely want independence?
No. 45% in a referendum is defeat. 45% in FPTP is a landslide.
> Because Labour are not "left wing" enough?
Possibly.
>Because Labour is perceived as (Islington) English?
YES. See Johan Lamont's comments when she resigned.
>Because Labour had taken Scotland for granted for too long?
YES, THIS.
SNP have a reputation for competence and representing Scottish interests.
Scottish Labour MPs were seen as lobby fodder and unseen in their constituencies. It's certainly my impression of my former MP who lost with a swing of 40% to the SNP. That might be completely unfair but perception largely determines where the cross on the ballot paper goes
A few other factors.
There are a lots of enthusiastic Yes voters.
There are few enthusiastic No votes.
SNP membership went from 26,000 to 110,000 since the referendum.
Membership rose by 10,000 this April.
That's my perspective and is shared by many non-SNP voters like me.